The fun never ends. I uncovered a rear axle seal leak, i pulled off the rear drum to paint them and it appears there's a leak as my shoes were covered in black grease. It's not leaking fluid near the inner seal where it would be visible by just looking under the vehicle at the back of the backing plate, it's just leaking inside the drum. Does this mean it's just the outer seal that is bad? And if that's the case can I just replace the outer, or do you compromise the inner seal to the point it needs replacement when you pull the axle?
Both seals and the bearing were replaced about 9,000 miles miles and 4 years ago due to the bearing going bad from a bent axle shaft. I installed a new axle at that time as well. I'm sure the seals were aftermarket and not Toyota.
Thanks for any help.

 

And the rear diff breather, is that supposed to move up and down or something? It doesn't move at all, seems like a rusted stub, no opening for air to flow in and out at all.

 

If the breathers not movable and not functioning as it should that could be the problem, pressure builds up and forces the gear oil past the seals....try to free it up first to see if it solves the problem.

 

First of all a clogged breather is not good, when that oil heats up and expands, your axle housing needs to breathe, if it can't breathe it will push oil out the seals, so there's a good chance that's what happened here. Also a chance that the seals were not installed properly, were nicked somehow or who knows what.

If it were me, I would order a new breather from Toyota, probably a couple of bucks. Also order 2 inner seals and 2 outer seals.

The big headache is you are going to have to press the axle out of the backing plate to get to that inner seal.

 

might as well pick up new bearing and keepers. they dont always come off very easily. i just usually cut the keeper and bearing off. makes getting to that outer seal alot easier.

 

The most logical option is to fix the breather and clean out the drum. Check it again in a week or two and if it's not leaking any more, replace the shoes (both sides). Problem solved. If it is still leaking, then dig into the seals and possibly the bearings (depending on play).

No need to start throwing parts at it, especially since the seals were replaced not long ago. Sure it's possible the seals weren't installed correctly, but a clogged breather will definitely cause leaks so that's where I'd start.

 

x2. Baby steps.

 

New breather ordered from dealer, I'll have it Friday. I'll install it, clean out the drum, and check it in a week or two. Fingers crossed that this will fix it.

 

I usually just soak the old rusted ones in mystery oil over night, then spray the snot out of them with brake clean, after that I use 100psi compressed air to blow any gunk left, and they should be good.

Taking them off and soaking in mystery oil over night every year or 2 prevents them from gunking/seizing up tho

 

My truck has some sort of rubber undercoating sprayed on it. Looks like they didnt tape off the breather when they did it, coated the breather.

 

Bummer, How much did the new breather run you? You get it right from toyota?

 

Yeah local dealer, $9.11.

 

Ok, wow, the breather was definitely not breathing. I just got back from the dealer with the new breather, crawled under the truck and unscrewed the old one and could hear the air pressure coming out as I got to the last thread!!!

So my question is, will this cure the axle seal leak I have or do the seals get damaged where they need to be replaced when they're under pressure like they were?

 

I wouldn't think the seals would be damaged just from oil being forced past them, especially if they are relatively new and flexible as yours should be. My inclination would be to run it with the new breather and see what happens before tearing into a seal project. You should be able to tell in just a couple of days if you're good or not.

 

I've pinpointed where the slow leak is coming from but nut sure of the terminology. It's leaking at the very end of the axle, between the 2 plates that the lug studs go thru, there seems to be a gasket between these plates, the gear lube is seeping between the plates and gasket.

 

^^Any thoughts on which seal is bad? Is it just that gasket that seems to be sandwiched between the plates?

 

I had a similar situation and it was an easy and cheap fix. Just disconnect your brake line, remove the 4 bolts that hold the axle in and slide it out. You don't need to remove brakes. Remove the seal and install a new one. If that doesn't fix your leak then you will need to replace the inner seal and it is a lot more involved. The outer seal isn't very expensive. That is what I would do before changing out both seals.

Maybe the correct way would be to change both seals but it is more involved then I know about changing the inner seal. Worked for me and no more leaks. Worth a shot.

 

Slight correction to Terrys87's post (based on reading I've done since my previous post). The seal he's talking about, the one in the end of the axle housing, is actually the one called the "inner" seal (it's the most inboard of the two seals). As he says, it's easily accessible once you slide the axle out. The other seal, the "outer" seal, is sandwiched between the bearing plate and the brake drum plate, and requires pressing the bearing off the axle and out of the bearing plate to access it to replace it.

The inner seal (as defined above) is the one that is actually responsible for keeping the oil inside the differential and axle housing. The outer seal is really more of a dust and water seal to keep crap out of the bearing. The axle bearing itself is packed with grease and doesn't receive lubrication from the differential oil. If the inner seal fails, diff oil seeps past it, through the bearing, past the outer seal, and then into the brake drum or to the outside world between the plates. It's possible the seepage you are seeing is just residual oil left over between the bearing and outer seal that hasn't worked it's way out yet.

From what I've read, the one danger is that the leaking oil can wash the grease out of the axle bearing, setting it up for eventual failure down the line. Don't know how big a risk that is. I just had exactly this same thing happen two weeks ago, and chose to do the simple fix first by changing the inner seal. We'll see how that goes. If the wheel bearing starts getting noisy, it'll be time to do the rest.

 

Great info guys, thank you! Maybe it is residual oil that I am seeing, I just replaced the breather as it was completely clogged, I'll check again in a couple weeks, so we'll see. There was no oil around that outer dust seal, just seeping between the plates. Thanks again.